A vehicle window regulator usually comprises a housing or support plate that is fixed to the panel forming the door of the vehicle, one or more arms supporting the window by means of various anchorage means, an operating motor mounted in the housing, which moves a gear that engages in a toothed portion of a toothed component that is attached at its opposite end to one of the arms supporting the window, so that the motor brings about the movement of the gear and the toothed component, giving rise to the movement of the arms and, as a result, the raising or lowering of the window. The window regulator may comprise a guide, which is also fixed to the vehicle door panel, to which one of the arms is attached in order to secure a guided movement of same.
As a rule, all the components of the window regulator device are pre-installed in the housing (including the drive motor), prior to its attachment to the door of the vehicle. In these cases, to carry out the installation of the window regulator on the vehicle door, first of all, the housing is fixed to a part of the door which lies in the interior of the vehicle and then the guide is fixed to the same part of the door. The window is set in place by means of the anchorage means and it is supported by the arms of the window regulator. During the window fitting operations the position of the arms remains fixed (they do not move under the effect of the weight of the window), as the toothed component is locked by means of the gear, which is held by the drive motor.
It could also be the case that the drive motor is not pre-installed, along with the other components, before the window regulator is fitted in the vehicle door. In this case, at the time of carrying out the installation of the window regulator in the vehicle door, the gear will be engaged with the toothed component, but without there being any braking mechanism between the two, so the toothed component may move in relation to the gear, which means that the arms may adopt a variety of positions during the installation of the window. We should be taking into consideration that the position of the arm at the time of the installation of the window should correspond to a specific position between the toothed component and the gear, which assures the full travel of the window during its operation, i.e. the window is raised or lowered fully. In this case, the drive motor would be fitted after installing the window regulator.
Invention patent JP 2000027532 refers to a retaining device in which the gear engages with the toothed component and is in turn engaged in some projections provided on a fixed plate that prevent it from moving. On the end of the shaft on which the gear is mounted there is a tapered spring that keeps the gear coupled to the plate in its expanded position. When the motor is fitted on the gear shaft, the gear exerts pressure and compresses the tapered spring so that the gear is released from the fixed plate while the gear and the toothed component are held in the engaged position.
In this case, when the motor is installed on the gear shaft, the gear withstands the torsion stress applied by the toothed component, which may damage the gear or require a degree of strength in its design that is unnecessary for its operation. The need to fit this plate also involves the occupancy of a space between the gear and the electric motor.
Furthermore, in invention patent DE 3 506 771 we observe a retaining device consisting of stops each limiting the travel of the toothed component in two possible directions. By means of this arrangement there is no locking as such, but rather travel limit positions, so a fixed position of the toothed component cannot always be guaranteed for the installation of the window.